Effect of Crystallinity of Microcrystalline Cellulose on Granulation in High-shear Mixer.

Abstract

Granulation was carried out using binary mixtures of microcrystalline cellulose (MCC) and cornstarch (CS); water was used as granulating liquid. The effect of crystallinity of MCC on granulation was examined using MCC pulverized by a jet mill (J-MCC) and a vibrational rod mill (R-MCC). Crystallinity of J-MCC was nearly equal to that of intact MCC (I-MCC), but that of R-MCC was remarkably low due to the mechanochemical effect. The growth rate of granules with R-MCC was greater than those with I-MCC and J-MCC; the latter two had a grnule having a core (MCC and CS) around which CS was layered. R-MCC provided granules in which CS and abraded MCC were homogeneously mixed. In addition, R-MCC remarkably decreased the difference in drug content among the size fractions of granules compared with I-MCC. These results suggest that the decrease in crystallinity of MCC may increase the tendency of its abrasion by shear force of impeller, because of an increase of the fragile amorphous region swollen by added water; this, in turn, results in a difference in the growth mechanism and in a greater growth rate.